As science and technology continue to develop, touch panels are widely applied to various types of electronic apparatuses. In addition to replacing buttons, use of touch panels generally allow electronic apparatuses to also benefit from enlarged display images.
Common touch panels in general are classified into various types including a resistive type, a capacitive type, an infrared type, and an ultrasonic type, for example. Since a capacitive touch panel includes advantageous features such as being dustproof and scratchproof as well as having a high-resolution, the number of electronic apparatus equipped with a capacitive touch panel has been on the rise.
A principle of the capacitive touch panel is that a layer of transparent conductive film (e.g., an antimony tin oxide (ATO) layer), placed on a glass substrate, serves as a sensing structure. When a user touches the capacitive touch panel with his finger, close proximity the finger to the touch panel causes variations in capacitance in the sensing structure and coupling capacitance within the sensing structure. The capacitive touch panel determines a location of the touch on the capacitive touch panel according to the capacitance variations in the sensing structure.
FIG. 1A shows a prior art capacitive touch sensing structure 1. The sensing structure 1 includes a substrate 10, a plurality of first electrodes 11, a plurality of first conducting wires 12, a plurality of second electrodes 13 and a plurality of second conducting wires 14.
A first direction X points from a first position X1 to a second position X2, and a second direction Y points from a first position Y1 to a second position Y2.
The first electrodes 11 are arranged in sequence from the first position X1 towards the second position X2 in the first direction X of the substrate 10. Each of the first electrodes 11, a triangular electrode, has its bottom located at the first position Y1 in the second direction Y of the substrate 10, and its top extended towards the second position Y2.
The first conducting wires 12 are respectively electrically connected with the first electrodes 11.
The second electrodes 13 are arranged in sequence from the first position X1 towards the second position X2 in the first direction X of the substrate 10. Each of the second electrodes 13, a triangular electrode, has its bottom located at the second position Y2 of the substrate 10, and its top extended towards the first position Y1. Further, the second electrodes 13 are staggered with the first electrodes 11 in an electrically isolated manner from each other.
The second conducting wires 14 are respectively electrically connected to the second electrodes 13.
Referring to FIG. 1B, when a user touches an area A of a capacitive touch panel with his finger, the capacitive touch panel senses a capacitance variance Q1a of a first electrode 11a and a capacitance variance Q2a of a second electrode 13a, and regards a capacitance variance Q1b of a first electrode 11b as an error term. A capacitance variance is proportional to a touched area, and a touched area of the first electrode 11a touched by the finger of the user, determined by an associated circuit, is greater than an actual touched area due to the error term contributed by the capacitance variance Q1b of the first electrode 11b. Therefore, a position in the second direction Y, by sensing the capacitance variance in the area A, is determined to be lower than an actual touched position.
When the user touches an area D of the capacitive touch panel with his finger, the capacitive touch panel senses a capacitance variance Q1d of a first electrode 11d and a capacitance variance Q2d of a second electrode 13d, and regards a capacitance variance Q2c of a second electrode 13c as an error term. Therefore, a position in the second direction Y, by sensing the capacitance variance in the area D, is determined to be higher than an actual touched position.
Therefore, when the user moves the finger in the first direction X on the capacitive touch panel, a position in the second direction Y, sensed by a conventional capacitive touch panel, varies up and down. A reason for such phenomenon lies in changes due to omitted error terms in the process of calculating the second direction Y in the prior art with an error up to 10 mm.
In the prior art, in order to reduce the error and increase accuracy of the capacitive touch panel, more finer first electrodes and second electrodes are provided on the substrate 10. However, more electrodes need more conducting wires. Corresponding detection circuit is complex and the number of pins connected to electrodes is increased, leading to increased production cost.
Therefore, without increasing extra conducting wires, a capacitive touch sensing structure and a sensing method thereof capable of more accurately obtaining a touched position on the capacitive touch panel are needed.